Double shades such as are disclosed in my U.S. Pat. No. 5,205,334 have a headrail that holds two independently operable shades. One shade is a roller shade in which shade material is wound on a roller within the headrail. The second shade is a pleated or cellular shade that is attached to the bottom of the headrail. Pleated and cellular shades have lift cords that extend from the bottomrail into the headrail. In some shades the cords are routed through a cord lock and extend out one end of the headrail. In other shades the lift cords are collected on an axle within the headrail. In the double shade disclosed in U.S. Pat. No. 5,205,334 the lift cords pass through a cord lock. This is typical of double shades.
Double shades as well as most other window coverings that have a headrail are usually assembled for particular installations rather than being stock items. Fabricators who sell double shades usually also sell pleated shades, cellular shades and roman shades. These shades have lift cords that either pass through a cord lock or are collected on spools or an axle within the headrail. In recent years the industry has been concerned about child safety and limiting the number of cords that are accessible in a window covering product. Therefore, window coverings that collect lift cords in the headrail are preferred from a child safety perspective. Prior to the present invention, the headrails used for double shades could not be used for single, pleated or cellular shades in which the lift cords were collected in the headrail. Instead, fabricators were required to maintain one headrail system for double shades and a different headrail system for single shades in which the lift cords were collected in the headrail. There is a need for a roller with removable cord collection spools that can be used in a headrail for double shades. Such a system would enable fabricators to maintain one headrail system that could be used for double shades, pleated shades, cellular shades and roman shades.
A typical double shade is shown in FIGS. 1, 2 and 3. A headrail 1 supports both a pleated shade 8 and a roller shade 12. End caps 2 and 3 are provided at either end of the headrail and a roller shade mechanism is mounted within the headrail. The headrail is attached to a wall or window frame 15 shown in chainline in FIG. 3. A wall mount may be made through bracket 11 or end caps 2 or 3. A ceiling or wall mount is made through bracket 11. The roller shade 12 is wound around roller 14 which rides on brackets that are preferably built into the end caps 2 and 3. The pleated shade 8 is mounted to the bottom 18 of the headrail 1. If desired, the front face 4 of the headrail can be extended by leg 32 as shown in FIG. 3 to obscure all or a portion of the fabric stack. The pleated shade material in the double shade of FIGS. 1 and 3 has tabs 9 which extend from the rear pleats of fabric 8. Each lift cord 7 passes through holes in the tabs 9 to bottom rail 6 of the pleated shade. The opposite end of each cord 7 extends through a cord lock 30 as shown in FIG. 3.
In U.S. Pat. No. 5,791,393 I disclose a shade operator which enables a roller shade to be operated by a single ribbon. This shade operator can be used in a double shade of the type shown in FIGS. 1 through 3. Consequently, if a cord collection spool could be substituted for the roller shade then the shade operator could operate a single pleated, cellular or roman shade attached to a double shade headrail.
Most cord collection spools for pleated, cellular and roman shades utilize a single axle about ¼ inch in diameter. The cord may be collected directly on the axle as disclosed in U.S. Pat. No. 5,194,660. Or, the cord may be collected on a spool attached to the axle such as is disclosed in my U.S. Pat. No. 6,644,372 and in U.S. Pat. No. 5,699,847. When the lift cords are collected on an axle or spools in the headrail it is necessary to assure that as the cords are wound and unwound so that each turn of the cord is adjacent the previous turn. If the turns of one lift cord overlap while the turns of another lift cord do not, the bottom of the shade will be tilted as the shade is raised and lowered. Most cord collection systems overcome this problem by moving the axle, moving the spools on the axle or moving a cord guide on or adjacent the axle, left or right as the axle turns. Such movement prevents overlap of the lift cords as they are wound and unwound.
Any roller which is used in a roller shade cannot move from left to right, or right to left as the roller rotates. Such transverse movement would impede the rolling and unrolling of the shade material. Since the roller cannot move transversely, it is necessary that spools be used to collect lift cords on a roller.
Several years ago the French company, Somfy, made a pleated shade in which each lift cord was wound on a spool that was fixed to a shade roller. The spools had a collar at either end and their positions on the roller could not be adjusted. Consequently, when the lift cords were wound onto the spools, the turns of each lift cord could overlap. This system was not in the marketplace very long. Furthermore, because the spools were firmly attached to the roller, one could not wind shade material on the roller. If one wanted to use the headrail for a roller shade, the roller with spools had to be replaced with a standard shade roller.
Somfy was able to design a system in which lift cords are collected on an axle or tube that did not move transversely. This system has a drum with a collar or shoulder for each lift cord and is disclosed in U.S. Pat. No. 5,328,113. A cord guide directs the lift cord onto a drum. The cord guide assures that the lift cord is initially collected on the drum adjacent the shoulder. Each turn of the cord pushes the previous turns toward and eventually onto the axle. Like the cord collection spools in other systems, the drums create projections along the length of the axle. Therefore, a roller shade cannot be wound about the axle in this system without being wrinkled or damaged.
Consequently, there is a need for a cord collection system having a roller that can be used for a roller shade. This roller must be able to receive spools that can collect lift cords while avoiding the cord overlap problem. These spools must be removable from the roller. There can be no projections from the surface of the roller after the spools are removed which would cause wrinkling of shade material wound on the roller.